Question: What is the material with Max hardness which is used as Fastener?
Paraphrase: What is the hardest material that is used as a fastener?
SPARQL (Wikidata): select ?ent where { ?ent wdt:P31 wd:Q214609 . ?ent wdt:P5483 ?obj . ?ent wdt:P366 wd:Q2002016 } ORDER BY DESC(?obj)LIMIT 5